This invention relates in general to devices and methods for quickly and inexpensively analyzing the impregnation potential, or fertility, of a sperm sample in a non-laboratory setting, and in particular to such devices and methods in which a user performs only a few simple mechanical steps to provide sperm input to a computerized module which automatically performs an analysis and provides a resultant figure of merit.
Over the past few decades, animals in general-from fish to humans-have demonstrated a substantial reduction in general fertility. In most species, the problem appears about equally in the male and the female partner. The decline has been attributed to pollution of the world""s environment, global warming, contra-Darwinian medical practices, selection of desirable traits without regard for fertility, and many other factors. The reality of that decline is certain and has been measured worldwide, but its causes are unclear.
In species that are important to humans the decline is often our fault. Some food animals have been carefully bred to meet specific tastes of humans, but at the expense of fertility of that species. As examples, turkeys and chickens bred to maximize white-meat production do so at the demonstrable expense of fertility. Even pets and work animals, selected over many generations for appearance or performance characteristics, have seen significant deterioration of fertility. Subfertility in poultry, cattle, pigs, and other food animals creates at least a billion dollar annual loss worldwide.
Regardless of the species, there are several techniques by which a female partner can be checked for fertility, including physical examination, hormonal workups, egg harvests, and other testing, but there are only two measurement sets by which a male partner can be checked: xe2x80x9csperm countxe2x80x9d and chemistry. By far the majority of subfertile males can be identified by characterizing their sperm count. It is extremely rare to discover a male with a chemical defect that is not accompanied by another problem identifiable by a sperm count. To determine xe2x80x9csperm count,xe2x80x9d some form of magnification is used to increase the apparent size of the spermatozoa, or sperm cells, and then they are xe2x80x9ccountedxe2x80x9d by a human or a computer. In some species there are more than one billion cells per milliliter. The fast-moving cells, therefore, are very small and difficult to quantify even with a microscope. Often, an optical grid is used to divide the sample into segments to facilitate accuracy. Whether by a human observer or a computer, the cells are counted to determine (1) the total number per unit volume, (2) the degree of motility, and sometimes (3) the general shape of the cells, or xe2x80x9cmorphology.xe2x80x9d The result of a sperm count is usually a report that includes these factors plus others, such as volume, color, pH, etc., that may reflect the general health of the male. But the overwhelmingly important single measurement, in virtually all species, is the number of motile cells available to penetrate the egg. For the purpose of this document, xe2x80x9csperm countxe2x80x9d refers to xe2x80x9chealthy sperm countxe2x80x9d: the concentration of cells capable of impregnating an egg.
As for treatment of subfertility, there are proven treatments by which the fertility of a female can be enhanced, including a spectrum of hormones; among food animals, certain veterinary drugs are available that work upon the female to increase the average litter size. But male fertility is another matter entirely. Regardless of species and despite the efforts of medical and veterinary sciences, only a very small percentage ( less than 1-2%) of subfertile males have conditions which can be treated to increase sperm count. In almost all cases, and in all species, there is no successful therapeutic approach to male subfertility.
In typical food animals, there is competition among the males to mate with multiple females. A subfertile male that is otherwise dominant may seek to impregnate many females, driving away less dominant but potentially more fertile competitors. This results in poor reproductive performance of multiple females and becomes very expensive. In veterinary fertility medicine, particularly as it applies to food animals, subfertility has a direct and calculable impact. It is therefore most advantageous to be able to quickly and inexpensively measure the impregnation potential of the males in a food stock so that the subfertile males can be culled from the stock, leaving only the fertile males to compete for the females.
The prior art for determining the impregnation potential or fertility of a semen sample basically includes only computer assisted semen analysis (xe2x80x9cCASAxe2x80x9d), microscopy, a device called the Sperm Quality Analyzer (xe2x80x9cSQAxe2x80x9d) and biochemical assays performed in a laboratory and therefore inappropriate for real-time analysis in the field. CASA is achieved with a microscope, one or more video cameras, video image conversion hardware, a computer, and one or more displays. CASA systems have been developed by three companies, at prices ranging from $30,000 to more than $50,000. They are generally considered too expensive for even hospital clinical laboratories, and are certainly too costly for food animal breeders, e.g. chicken breeders. As for microscopy, a conventional laboratory microscope is used, usually in conjunction with a device that presses the sample into a very thin film against a finely etched grid to facilitate counting. This method is time consuming, expensive especially in terms of labor, and the results are subjectivexe2x80x94based on a person""s ability to count the density of spermatozoa in a unit volume.
The SQA is a computerized device that has been used by sperm banks, fertility clinics, and laboratories to measure certain characteristics of sperm. A sperm sample is drawn into a transparent capillary with precise internal dimensions. After a sample rises into the capillary, the carrier is inserted into an elongated slot wherein a calibrated light is directed by a fiberoptic conduit to illuminate a small segment of the capillary. At a side of the capillary opposite the light is a photosensors which senses the occurrence and frequency of very small perturbations in the light passing through the capillary. These perturbations, which are caused by movement of the sperm cells within the capillary, are converted to digital data and communicated to a computer. The computer applies a known algorithm to the data and produces a numerically expressed Sperm Motility Index (SMI) which is on an arbitrary scale which reflects overall sperm quality or relative fertility of the sperm samples. SMI values for humans range from 0 in complete asthenzoospermic azoospermic patients to over 160 SMI units in good quality sperm. It is essentially a measurement of the number of motile cells and the nature of their motility.
This invention uses some of the principles of the SQA (optically sensing motion of sperm within a certain amount of semen) to produce a fertility figure of merit, e.g. an SMI or similar datum, but overcomes many of the problems encountered by the SQA. Moreover it includes processes which are novel and unique over those used in the SQA. It also provides features not seen or known in connection with the SQA, for example, features which make this invention adaptable to unclean animal environments. In this regard, the SQA was designed for a laboratory environment and has serious problems with contamination of the slot into which the carrier is inserted to make a reading. Minute specks of dirt can easily get into the slot and cause erroneous readings, and the device has to be significantly disassembled to clean the slot. This invention is much less likely to be contaminated, and if so, it is quickly and easily cleanable. This invention also provides a plurality of portable measurement modules each pluggable into a case for charging and interfacing with at least a printer and display. Also, the SQA takes forty seconds to provide an SMI value because it performs its basic test four times for accuracy. This invention provides a novel, disposable capillary carrier which enables a measurement module to perform multiple tests in parallel, thus reducing the time per analysis to a fraction of the SQA""s time, enhancing practicality in the food animal industries.
This invention is the most cost effective technique to determine male fertility whether it is used for humans or animals. This is due to the need for only inexpensive equipment (as will be seen), minimal user training, low per-test consumables cost, and rapidly displayed results. The last is very important because in the fertility measurement business, time is money. Another important advantage is the complete lack of subjectivity in achieving results. The computer makes all judgements. Multiple parallel samplings by laboratory scientists produces a broad bell-shaped curve of results because of inherent subjectivity, but with this invention parallel measurements are very consistent and the results are defined by a xe2x80x9cspikexe2x80x9d rather than a bell curve.
An example of how this invention can be advantageous concerns the chicken industry. xe2x80x9cBroilersxe2x80x9d are those chickens raised to become meat. The U.S. broiler industry hatches approximately 9 billion birds per year, at an efficiency much higher than anywhere else in the world. These 9 billion eggs hatch from about 10.7 billion laid by approximately 70 million hens, which are fertilized by about 7 million roosters. But a significant percentage of the roosters are subfertile, resulting in a loss of about 16% of all eggs laid, or about 1.7 billion. Until now there has been no practical, cost effective way to differentiate between fertile and subfertile roosters, hence the industry has heretofore achieved only an 84% hatchability rate. However, a study done at the Mississippi State University by Chris McDaniel, PhD, using an SQA found positive correlations of the SMI with sperm-egg penetration and live sperm concentration, but negative correlation with the percentage of dead sperm. Dr. McDaniels concluded that these correlations indicated that the SMI can used to improve broiler breeder males for fertilizing potential. During his study, Dr. McDaniel developed what is now known as the xe2x80x9cMcDaniel protocolxe2x80x9d which defines an SMI scale to be used for roosters and also defines the ratio a rooster sperm sample must be diluted. Dilution is necessary because rooster semen has concentrations of billions of cells per milliliter, the dilution moves the concentration into the most linear range ofthe instrument. The preferred dilution is one part sperm to five parts diluent which is a simple saline solution. In this regard, this invention also includes a means for quickly, cleanly, accurately, and inexpensively diluting a rooster""s or any other species"" sperm sample in the appropriate ratio.
In summary, this invention presents a simple, cost-effective, and proven methodology by which subfertile roosters, or the males of any other species, can be identified and culled from a breeding group, thus improving fertility and the resulting number of progeny.
Other advantages and attributes of this invention will be readily discernable upon a reading of the text hereinafter.
An object of this invention is to provide a portable system for quickly, accurately and inexpensively analyzing on-site the impregnation potential, or fertility, of multiple male animals, xe2x80x9con-sitexe2x80x9d meaning where the animals are kept, e.g. a barn, hen house or even in a field.
A further object of this invention is to provide such a system in which a user performs on-site only a few simple mechanical steps (e.g. aspirating semen into a carrier, inserting the carrier into a portable analysis module, pushing a button) to quickly get an indication of fertility.
A further object of this invention is to provide a system as described in the preceding paragraph which produces a sperm motility index (xe2x80x9cSMIxe2x80x9d) value or other index of relative fertility.
A further object of this invention is to provide a system as described in the two preceding paragraphs which can be used in unclean animal environments.
A further object of this invention is to provide a system as described in the three preceding paragraphs in which individual sperm samples are collected in inexpensive sperm carriers which are placed in a measurement module for analysis and then preferably discarded.
A further object of this invention is to provide a system as described in the preceding paragraph in which the sperm carrier is further designed to permit calibrated dilution of a sperm sample within it.
A further object of this invention is to provide a system as described in the preceding paragraphs in which a plurality of measurement modules are pluggable into a module carrier for energizing and for interfacing the modules to at least a printer and display.
A further object is to a system as described in the preceding paragraphs which has at least one additional optical path through the carrier for obtaining readings other than motility, e.g. for obtaining a semen-absent reading for measuring sperm density along with motility.
A further object is to a system as described in the preceding paragraphs which is further capable of measuring the sperm density of a semen sample along with motility.
A further object of this invention is to provide a system as described above in which a sample carrier which exhibits a code readable by a processor for identifying the species from which the sample was obtained.
A further object of this invention is to provide a system as described in the preceding paragraph in which the code is made illegible to the processor after a time by action of a semen sample solution.
These and other objects, expressed or implied, are accomplished by a sperm analysis system which has a sperm sample carrier and xe2x80x9creaderxe2x80x9d module. The sperm sample carrier includes: (1) a shank defining a chamber and an opening into the chamber for ingress and egress of a sperm sample, (2) a manually operated pump for aspirating a sample of sperm into the chamber, and (3) a plurality of distinct photon paths intersecting and passing through the chamber. The module includes: (1) a processor responsive to an actuation signal from an operator, (2) a photon source, e.g. a light source, energized by the processor in response to the actuation signal, for sending respective beams of photons through each of the photon paths, (3) a plurality of photosensors, one for each photon path, each for producing a signal indicative of the occurrence and frequency of perturbations in the beam of photons passing through said each""s respective photon path and communicating the signal to the processor, (4) an algorithm run by the processor for processing the plurality of photosensors signals to produce a quantified figure of merit indicative of the motility of sperm within the chamber, (5) and means for communicating to an operator the figure of merit. Preferably the photon source means comprises a light source and a plurality of photon conduits, e.g. fiber optic cables, each conduit receiving photons from the light source and directing them to enter one end of a respective photon path, a respective photosensors being disposed at an opposite end of the path to sense the photons leaving the path. Preferably the system also includes indicia disposed on the sperm sample carrier for conveying to the processor the biological classification of a donor of a sperm sample within the carrier""s chamber. Preferably the system also includes a tray defining a plurality of closed cavities, each cavity containing a precise amount of semen diluent. Preferably the cavities are closed by a frangible seal which can be breached by the shank of a carrier to expel a semen sample from the carrier into the diluent and to stir them together, the mixture then being aspirated in the carrier for testing.